<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .A {
      float: left;
      width: 800px;
      height: 200px;
      background-color: pink;
    }
    .B {
      float: right;
      width: 200px;
      height: 200px;
      background-color: blue;
    }
    .C {
      float: right;
      width: 200px;
      height: 200px;
      background-color: green;
    }
  </style>
</head>
<body>
  <div class="A"></div>
  <div class="B"></div>
  <div class="C"></div>
</body>
</html>